Visual MODFLOW Flex

Groundwater Flow & Contaminant Transport Modeling Software

Visual MODFLOW Flex brings together industry-standard codes for groundwater flow and contaminant transport, essential analysis and calibration tools, and stunning 3D visualization capabilities in a single environment.

Visual Modflow for Groundwater Flow & Contaminant Transport Modeling Software

What's New in Visual MODFLOW Flex 9.0

Experience the new version release of Visual MODFLOW Flex 9.0
See what was included in Visual MODFLOW Flex 8.0
For a complete version history, see the Visual MODFLOW Flex readme file


Visual MODFLOW Flex now supports MODFLOW-6, the newest core version of the groundwater modeling code developed by the USGS. MODFLOW-6 is based on a redesigned framework that supports 3D groundwater flow, solute transport, and various processes with an all new and more legible input file structure for both structured and unstructured grids.

The following MODFLOW-6 flow packages are supported in Visual MODFLOW Flex:

  • Simulation Packages:
    • NAM – Simulation Name File
    • TDIS – Time Discretization
    • IMS – Iterative Model Solution


  • Groundwater Flow Model (GWF): Simulate saturated groundwater flow using structured finite difference grids or unstructured control volume finite difference grids (Voronoi or Quadtree).
    • NAM – Groundwater Flow Model Name File
    • DIS – Discretization Package
    • DISV – Discretization by Vertices Package
    • IC – Initial Conditions (Heads)
    • OC – Output Control Package
    • NPF – Node Property Flow Package
    • STO – Storage Package
    • CHD* – Time Varying Constant Head Package
    • WEL* – Well Package
    • DRN* – Drain Package
    • RIV* – River Package
    • GHB* – General-Head Boundary Package
    • RCH – Recharge Package
    • EVT – Evapotranspiration Package


  • Solute Transport Model (GWT): Simulate groundwater solute transport using structured finite difference grids or unstructured control volume finite difference grids (Voronoi or Quadtree), including a variety of sorption, reaction, and immobile domain models.
    • NAM – Groundwater Transport Model Name File
    • DIS – Discretization Package
    • DISV – Discretization by Vertices Package
    • IC – Initial Conditions (Concentrations)
    • OC – Output Control Package
    • ADV – Advection Package
    • DSP – Dispersion Package
    • MST – Mobile Storage Transfer Package
    • IST – Immobile Storage Transfer Package (up to three immobile domains)
    • SSM – Source Sink Mixing Package
    • CNC* – Time Varying Constant Concentration Package
    • SRC* – Mass Source Loading Package

Multiple Instance Packages: MODFLOW-6 allows you to include multiple instances of certain packages (marked with * above) in a simulation and track budgets separately for each package.

  • Support for ZoneBudget-6: Evaluate sub-regional flows for your groundwater flow models using MODFLOW-6.

Engines and Packages:

  • Assign Grid (In)active cell zones using data objects: You can use point, polyline, and polygon data objects to set the active/inactive flag for grid cells in the Finite Difference grid workflows


  • Import MNW1 Wells from Classic Projects: Well information using the MNW1 well model in Classic Projects can be imported into Visual MODFLOW Flex


  • Minimum thickness for Unstructured Grids: You can specify a minimum cell thickness below which unstructured grid cells will be removed from the grid so that you have more control on grid design around pinchout areas.


  • MODPATH with SEAWAT: You can run a MODPATH particle tracking simulation based on a SEAWAT flow (and transport) run.


  • Compare: Compare results for heads, drawdowns, or concentrations between two model runs using the same unstructured grid.

Performance, Usability, and Other Enhancements:

  • The unstructured grid workflow now uses the more familiar and intuitive conceptual well controls that uses coordinates and well screen information instead of cell indices
  • You can specify default Total and Effective Porosity values at the Define Modeling Objectives step
  • You can add particles for a particle track simulation based on Well objects in the Model Explorer as well as in the Data Explorer
  • Improved speed and performance saving and loading projects
  • You can specify a custom default project save location to save time when creating new projects
  • New Keyboard Shortcuts:
    • Press CTRL+T at the Translate Step to translate a model
    • Press CTRL+R at the Run Step to run a model

Visual MODFLOW Flex Applications include

  • Delineate well capture zones for domestic water supply development
  • Design and optimize pumping well locations for mine dewatering projects
  • Determine contaminant fate and exposure pathways for risk assessment
  • Simulate surface water-groundwater interactions
  • Watershed scale/regional groundwater modeling, and aquifer storage and recovery (ASR)
  • Evaluate groundwater remediation systems (pump and treat, funnel and gate etc)
  • Evaluate saltwater intrusion

Why Choose Visual MODFLOW Flex?

Visual MODFLOW Flex

Build models faster and more efficiently

  • Model inputs and grid design can be updated at any point in the modeling process as modeling objectives change, more data are collected and a better understanding of the sub-surface is achieved.
  • Modeling steps are conveniently presented in an intuitive, workflow-driven graphical user interface: see current and completed steps, and steps you need to finish.
  • GIS-based 3D conceptual modeling and numerical modeling all within a single integrated software environment. This reduces costly 3rd party pre-processing tools, and eliminates transfer errors.

Build larger, more complex credible models

  • Equipped to handle vast quantities of detailed, high resolution data. Simulate large and complex regional-scale groundwater systems.
  • Model inputs and outputs can be easily visualized alongside raw GIS field data in 3D, allowing credibility by demonstrating numerical model data generation (model layers, flow parameters, recharge data) from conceptual data (borehole logs, GIS data).
  • Unique design permits easy side-by-side comparisons of multiple models allowing you to assess alternative modeling scenarios, grid indiscretions and hydro-geologic interpretations.

Powerful Data Visualization

Built and designed on the latest in 3D visualization technology, Visual MODFLOW Flex allows you to effectively present and communicate your data to colleagues and stakeholders with impressive visual renderings of your hydrogeologic model.

  • Visualize all data, including conceptual objects, numerical grids, input data (property zones, boundary condition cells) and output data (calculated heads, pathlines, water table) in state-of-the-art 2D, 3D and multi-view (FlexViewer) displays.
  • Create cut-away and cross-sectional views that allow you to see inside your model.
  • Generate 3D animations and movies for reports or the web, and optimized OpenGL graphics for enhanced hardware rendering.
  • Add isolines, contours, pathlines and color shading to viewers.
  • Drape raster images (site maps, satellite imagery) over 3D surfaces to show relief

Efficiently Manage Multiple Models

Most modeling projects involve several scenarios/versions, e.g., steady-state vs transient, different properties, inputs and grid types. Visual MODFLOW Flex allows you to assess uncertainty and improve model credibility through comparisons and analysis of multiple modeling scenarios – all within a single project.

  • Manage multiple model scenarios in a single project, and make direct visual and numerical comparisons between different modeling scenarios.
  • Easily generate multiple models in parallel for evaluating alternative hydrogeologic interpretations and hypotheses.
  • Calculate head differences between multiple model runs, with the same or different grid size.
  • Compare and analyze multiple modeling scenarios for selecting the best, most realistic model.

Full GIS Integration

Easily construct your grid-independent hydrogeologic conceptual model in minutes using existing GIS data sets.

  • Quick and easy data importing of all common file types and formats.
  • Automatic coordinate system and units conversion on import, and automatic data validation and intelligent error checking on import.
  • Define model boundaries, property zones, boundary conditions and attributes from imported GIS data.

woman in front of screen

Integrated 3D Conceptual and Numerical Groundwater Modeling

Visual MODFLOW Flex provides a seamless transition from raw data through conceptualization to the numerical model all within a single intuitive modeling environment.

  • Define complex geology and model layers using borehole log data and cross-sections
  • Interpret GIS data to define hydrogeologic properties and boundaries independent of the grid
  • Run, analyze, and validate model results with raw data in 2D, 3D, and cross-section views
  • Easily create multiple conceptualizations; generate numerous grids and model scenarios in parallel all in a single project
  • Assess uncertainty though comparing heads from multiple model runs in 2D, 3D or chart views

Flexible Grid Options

Visual MODFLOW Flex provides various grid types from which you can generate your numerical model. Easily experiment with different grid types and choose the one that gives you the best, most stable model.

  • Choose from various structured and unstructured grid types to accommodate a wide range of applications and geologic conditions (e.g., pinch outs, discontinuities).
  • Improve simulation accuracy, reduce runtimes and increase model stability with unstructured grid types (MODFLOW-USG)
  • Easily generate multiple grids within the same project and compare side-by-side in 2D or 3D
  • Perform grid refinement around areas of interest
  • Create faster more stable models with nested child grids that contain local horizontal and vertical refinement (MODFLOW-LGR)
  • View all supported grid types 

Get Started With Visual MODFLOW Flex